CEKAJIBYCID^E. 499 



of girdling is unknown to the insect, whose life is too short 

 to foresee the necessities of its progeny during the succeeding 

 season. 



"This insect maybe seen in Pennsylvania during the two 

 last weeks in August and the first week in September feeding 

 upon the bark of the tender branches of the young hickories. 

 Both sexes are rather rare, particularly the male, which is rather 

 smaller than the female, but with longer antenna?. The female 

 makes perforations in the branches of the tree upon which she 

 lives (which are from half an inch to less than a quarter of an 

 inch thick), in which she deposits her eggs ; she then proceeds 

 to gnaw a groove of about a tenth of an inch wide and deep 

 around the branch, and below the place where the eggs are 

 deposited, so that the exterior portion dies and the larva feeds 

 upon the dead wood and food which is essential to many 

 insects, although but few have the means of providing it for 

 themselves or their progeny by an instinct so remarkable. 



" Where this insect is abundant, it must cause much damage 

 to young forests of hop-poles by the destruction of the prin- 

 cipal shoot. We have known insects which, from 

 their rarity, could hardly be regarded as 'noxious,' 

 increase to such an extent as to be very destructive, 

 and the locust trees (Robinia pseudacacia) have had 

 their foliage withered during the few last summers 

 from such a cause (Cecidomyia robinioe Hald.) which 

 lias caused these trees to wither since that period, 

 particularly in August, 1868." The Tridentate 

 Compsidea, C. triderttata Oliv. (Fig. 490, larva, en- 

 larged three times), is a dark brown beetle, with a 

 rusty red curved line behind the eyes, two stripes on Fl '- 49 - 

 the thorax, and a three-toothed stripe on the outer edge of 

 each wing-cover, and is about half an inch long. It lives under 

 the bark of elms, occasionally doing much damage. (Harris.) 



The larva of Psenocerus supernotatus (described by Say) which 

 burrows in the stem of a climbing plant, supposed to be 

 the grape, Osten Sacken describes as being three-tenths of an 

 inch long, subcylindrical or prismatical, the pro- and meso- 

 thorax being a little broader than the other segments, and the 

 whole body sparsely beset with fine golden hairs. 



